Spatial contagion of predation risk affects colonization dynamics in experimental aquatic landscapes

Abstract

Colonization rate is a critical factor determining abundance and diversity in spatially distinct communities. Beyond simple variation driven by random processes, many species select/avoid habitat patches based on variation in habitat quality. Perceived habitat quality and colonization dynamics of individual patches may be influenced by specific characteristics of neighboring patches. We demonstrate that abundance and diversity of colonizing aquatic beetles is a function of both spatial variation in predator presence/absence and risk contagion generated by the proximity of predator patches to predator-free patches. Spatial contagion of predation risk generated repulsive sources: high fitness patches that were avoided. Thus, colonization dynamics of spatially discrete communities depends not only on intrinsic patch characteristics, but on the specific characteristics of nearby patches. The landscape-level dynamics of communities and metacommunities, as well as the efficacy of habitat restoration and conservation efforts, depends on how habitat quality is assessed, correctly or incorrectly, by colonizing species.